1. Field of the Invention
The invention relates to a loudspeaker box in the supporting structure of a motor vehicle.
2. Description of the Related Art
Automobiles usually have a sound system installed in them, merely as standard or as special equipment, which has a radio, a cassette player and a CD player, for example. In addition, a better sound system comprises a box system which has tweeters and woofers.
Since the loudspeakers radiate their sound to the vehicle interior, interference problems are avoided by connecting said loudspeakers to a resonance volume which is not connected to this interior. To this end, it is known practice to integrate particular cavity volumes, what are known as loudspeaker boxes, at suitable locations in the vehicle, but this usually results in a reduction in the available storage volume in the motor vehicle or takes up volume in the door lining.
German laid-open specification DE 197 35 082 A1 describes the coupling of a small loudspeaker box with a small resonance volume, which is fitted beneath the driver's seat, to a larger cavity volume (sill volume) which is already present in the motor vehicle in order to increase the size of the resonance volume associated with a loudspeaker. In this case, both the small loudspeaker box and the wall of the cavity volume have an opening, said openings being attuned to one another. In order to achieve acoustic coupling for the two resonance compartments, the loudspeaker box needs to be mounted with an exact fit on the wall of the cavity volume, so that the openings in the wall and the loudspeaker box lie on top of each other for the passage of sound.
Particularly for the output of frequencies below 150 Hz, bandpass boxes are particularly suitable. These exhibit a high level of pulse cleanliness and at the same time have low distortion, dynamic pulses and a high level of efficiency. The operating principle is already described in FR 1 587 761 A1 and comes from the fact that each side of a loudspeaker's diaphragm is assigned a dedicated chamber. Low-frequency sound reaches the outside only via a reflex opening arranged on a chamber. This gives rise to a spring action which has equal effect on both sides of the diaphragm, so that nonlinear distortions are reduced.
German laid-open specification DE 199 09 143 A1 describes the possibility of integrating a box into the supporting structure of a motor vehicle. This document proposes fitting a partition within a sidemember of the motor vehicle parallel along the longitudinal progression thereof, in order to split the supporting structure into two cavities which are separate from one another. A loudspeaker is fitted into this partition such that each of the two sides of the diaphragm is adjoined by one of the cavities. Tunnel-like deflecting ducts route sound waves produced by the loudspeaker in the supporting structure out of the latter into the vehicle compartment such that they emerge into the vehicle interior essentially transversely with respect to the longitudinal direction of the vehicle. The two bass outlet openings are in this case arranged at a distance from one another such that their distance is attuned to the sound waves propagating in the cavities, so that a kind of transmission line box is obtained.
It is an object of the invention to provide a loudspeaker box in combination with the supporting structure of a vehicle and which has good acoustic properties and can be produced without great mechanical design complexity.